It looks rolled, so they are extruded. It doesn't mean anything for what we are doing here, it is just curiosity on my part. It is the method by which they are produced. Pressed are just that, the clay body is pressed into a mold. Extruded runs the clay through a machine that extrudes it through an opening and the brick are then cut to length. Most brick of that age in the US are pressed, and they may well be in Britain, but those do not appear to be.

ah, interesting. They come from old buildings but they are from internal walls so they might not be as old as the buildings themselves. Certainly the brick in the picture in this thread looks different from the bricks i picked up last night from a different tenement. I'll crack one of them tomorrow night and have a look at the grain.

That's good news about the bricks. Thanks for the help. Hopefully start building in the next few weeks and I'll get the project posted up.

One way to tell for certain is if any are frogged or lettered on the big side. If so, then they are pressed.

The good news is that if they are from interior walls or wythes, then they are probably in better shape than the exterior brick. The bad news is that they used to use the softer brick (salmons) on the interior wythes and walls.

Steve,
they look good to me. Breaking into larger pieces rather than crumbly bits is good. To satisfy your curiosity (and mine) get a chunk from the centre of the brick and see if it crumbles at all between the thumb and fingers. If not, the go for it, if they do crumble, then I would find a batch that doesn't. This simply means that the bricks were fired hard but not for long enough th get the heat completely through the brick for thorough vitrification.

Mitch

Quote:

Are those red pavers a good substitute for firebricks?
I have my eye out for second hand reds - but I see those pavers for sale all the time...

Have you read Russell Jeavons' book on "Your brick oven, building it and baking in it"?
He has a restaurant at Willunga, south of Adelaide and has 2 wood fired oven in there. Both are built with common red bricks (in fact he has built numerous ones without a firebrick at all). In his larger restaurant oven, he has 2 layers of 2" clay pavers for his hearth. Also Littlehampton Bricks in the Adelaide hills at Littlehmpton, sell many more solid 4" clay pavers for wood fired oven builds than they do firebricks. They are fired at 1200˚C and cause no problems at our oven temps of around 500˚C and less.

Did as you said and it didn't crumble. The centre is actually really hard.

Hi Tscarborough,

The batch i picked up the other night has really clear writing: 'Wilson and Sons: Patent'. I've googled it in the hope that it might throw up a bit of history about the firm but to no avail.

Lastly, cause these bricks are recycled there isn't really any that would make a nice 'smooth' floor. So I'm thinking that I might splash out and buy firebricks just for the floor. Are old pressed reads the only material except from firebricks that can be used for the floor?

Ross,
If they don't crumble then they're fine.
I would use those bricks for the build and you might also look for some fired clay pavers, either 4" thick or a double layer of 2" pavers. Russell Jeavons who has a pizza restaurant in one of Adelaide's southern wine areas builds ovens with pressed red bricks and uses a double layer of 2" clay pavers for the hearths.
Good luck.

It is the material the bricks are made of that is the most important factor, rather than the temp they are fired to. Just because a brick is harder does not mean that it is more suitable. The method of manufacture of the brick, pressed or wire cut should not make much difference, although most wire cut bricks are full of holes and therefore unsuitable. A firebrick is not vitrified and may be softer than a pressed red, yet is able to withstand greater thermal shock and much higher temps. Clays containing a lot of iron (red) are often unsuitable and have a tendency to melt because of the fluxing effect of the iron,although this will not occur at the lower temps we use. The problem we face is the rapid temp increase and resultant thermal shock. Clays with a high alumina content are more suitable and generally these tend to be lighter in colour. I've seen plenty of fireplaces with red bricks that have spalled, although these are pretty old fireplaces and have no doubt seen way more service than we give our ovens. Therefore, I suspect that the pressed reds are quite suitable for our purposes.

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